With reference to the accompanying drawings, a conventional method of manufacturing chip inductor will be described hereinafter.
FIG. 18 illustrates a conventional manufacturing process of a chip inductor, FIG. 19 is a cross sectional view of the chip inductor, and FIG. 20 is a perspective view of the chip inductor.
In FIG. 18 through FIG. 20, the conventional method of manufacturing the chip inductor comprises a first step of forming conductive layer 32 on rectangular prism substrate 31 made of insulating material of approximately 0.5 mm square by 1 mm in length, a second step of forming coil portion 35 having spiral conductor 33 and groove 34 by slitting the conductive layer 32 spirally with laser 37, a third step of forming electrodes 36 at both ends of the coil portion 35, and a fourth step of forming outer coating 39 by coating the coil portion 35 with insulation resin 38, followed by heating.
In the fourth step, the coil portion 35 is coated on its entire periphery with the insulation resin 38 by rolling the substrate 31 in a direction of (A) on a tape coated with the insulation resin 38.
Thereafter, the insulation resin 38 is heated to form the outer coating 39.
In the above-described method of the prior art, since the insulation resin 38 is coated while rolling the substrate 31 on the tape coated with the insulation resin 38, an external shape of the insulation resin 38 enclosing the prism substrate 31 becomes cylindrical, as shown in the cross sectional view of FIG. 19, due to its surface tension.
The chip inductor is especially susceptible to an influence of surface tension of the insulation resin 38, because of very small external dimensions of its main body, which is approximately 0.5 mm square by 1 mm in length.
This causes a surface of the outer coating 39 to become round, thereby giving rise to a problem that it can not be mounted properly to a circuit board or the like as it rotates when it is mounted.
The present invention addresses the above-described problem, and is intended to provide a method of manufacturing chip inductor that makes a mounting surface of the outer coating flat, so as to assure reliable mounting.